Dual purpose injection line apparatus



J n 20, 9 C. E. WAKEFIELD, JR 3,326,234

DUAL PURPOSE INJECTION LINE APPARATUS 2 Sheets-Sheet 1 Filed March 9. 1964 /Zab Jum 1967 c. E. WAKEFIELD IR 3,326,284

DUAL PURPOSE INJECTION LINE APPARATUS 2 Sheets-Sheet 2 Filed March 9, 1964 INVENTOR. C/Mfidfi .5. Ma /754% BY United States Patent Ofiice 3,326,284 Patented June 20, 1967 tion of Pennsylvania Filed Mar. 9, 1964, Ser. No. 350,209 5 Claims. (Cl. 166.5)

The present invention relates generally to the control of oil and gas wells, and more particularly, relates to a system for applying valve control fluid under pressure to a safety valve actuator on a well production conduit and maintaining fluid pressure on said safety valve by displacing a piston with injection fluid pressure.

Oil and gas well heads, particularly underwater well heads, frequently have safety shutoff valves which are operated hydraulically with a hydraulic control line. Fluid pressure from other sources, for example, the fluid pressure on fluid being injected into a well for secondary recovery, can be utilized for such safety valve hydraulic control fluid; however, the pressure exerted on such injection fluids is often greater than that which can be tolerated by the safety valve actuator, or the injection fluid pressure is subject to periodic increases which would be detrimental to the safety valve actuator. In order to prevent damage to the safety valve actuator a reducing regulator has heretofore been used to reduce the pressure on the injection fluid to the pressure level tolerable for safety valve actuation. The use of a reducing regulator in this function, however, requires a relief valve and a return line. Furthermore, the regulator diaphragm is subject to deterioration and eventual rupture.

It is, therefore, an object of the present invention to provide a fluid operated safety valve system whereby the safety valve actuating fluid is displaced by a system fluid.

It is a further object of the present invention to provide an underwater safety valve hydraulic system adapted to utilize injection fluid pressure for displacing the valve control fluid, with a snubber device.

It is also an object of the present invention to provide an underwater safety valve control system which utilizes well injection fluid pressure to hold a safety valve open whereby the well injection fluid and the valve control fluids do not commingle.

Other objects and a more complete understanding of the present invention may be had by reference to the appended claims taken in conjunction with the following specification and drawings, wherein:

FIG. 1 is a schematic showing of an embodiment of the present invention used in conjunction with an offshore production well head;

FIG. 2 is an enlarged cross sectional elevation of the snubber device of my present invention.

Referring generally to the drawings, an offshore well head is shown with a snubber 12 interposed between the injection line 14 and the fluid operated safety valve actuators 16 and 17 on the well head. The primary flow of the injection fluid through injection line 14 is through the casing outlet 18 and into the well 20, as required by the secondary recovery program. The snubber 12 is subjected to injection fluid pressure through a bypass line 14a and serves to limit the fluid pressure used to hold open the safety valve 16 so that the safety valve actuator is not subjected to the excessive pressures or pressure fluctuations which may occur in the injection line 14.

Referring now more specifically to FIG. 1, the production head 10 is installed at the formation 11 on a production well 20 drilled into a formation underlying a body of water, although the present invention may also be used in conjunction with production heads in onshore applications. Production from the well 20 flows through tubing 22 and the tubing outlet 24 into the flow line 26.

A safety valve 16 is positioned at the tubing outlet 24 to shut in the well in the event of an unusually high or low pressure condition in the flow line 26. This safety valve may be of the conventional spring loaded valve actuator type wherein the safety valve is held open by fluid pressure applied through a fluid control line 28a. An increase or decrease in pressure in the flow line actuates the valve closing mechanism to close the flow through the well tubing outlet 24. Fluid pressure may be similarly suppilgiled to the casing outlet safety valve 17 through line 2 The present invention utilizes the fluid pressure present in the injection line 14 to displace the valve control fluid in the fluid control lines 28a and 28b which operates the spring loaded valve actuators 16 and 17 on the tubing and easing outlets respectively. In my present invention the valve control fluid may be any fluid selected to minimize corrosion or other potential damage to the safety valve actuators.

The injection fluid exerts pressure on the valve control fluid through snubber 12 by moving the floating snubber piston 30 (FIG. 2) so that the piston displaces valve control fluid in the cylinder chamber 32.

As best shown in FIG. 2, the snubber consists of a cylindrical body member 34 having apertured end members 36 and 38 welded to or formed integrally with cylinder 34. The orifice 40 is equipped with a valve control fluid fitting 39 through which the valve control fluid pressure in line 28 is maintained by the displacement of fluid in chamber 32 against the spring in valve actuator 16. The injection fluid orifice 42 is also equipped with a fitting 41 with which the injection bypass line 14a is connected to the snubber and through which the injection fluid enters cylinder chamber 33.

The floating piston 30 is equipped with a pair of packer seals 44 and 45 to prevent the injection fluid from entering the valve control line. The piston 30 may be of any conventional design for example it may be a solid member or a pipe 31 may be used to connect the piston members 30a and 3% as shown in FIG. 2. The snubber body member may have a weep hole 46 therein to prevent any injection fluid which may leak past the packer 44 from entering control fluid line 28. The snubber body may be equipped with a relief valve fitting at 48 through which any injection fluid leaking past seal 44 may be removed and prevented from entering the control fluid line 28. A gasket 51 and alignment dowel pins 50 may be provided between the snubber body halves 34a and 34b when the body halves are fastened together as with bolts (not shown).

The pressure exerted on the safety valve actuator 16 is a function of the compression load on the spring in the valve actuator which in turn is a function of the displacement of the piston in the valve actuator. This displacement can be limited by controlling the displacement of the piston 30 within cylinder 32. This control can be accomplished by limiting the amount of fluid transmitted to the safety valve actuator through the control fluid line by limiting the extent to which the piston 30 can move in the snubber chamber 32 as with threadable stud 60 to stop or limit the movement of piston 30 in chamber 32. The maximum pressure exerted on the safety valve actuator may then be varied by changing the length of the stud 60 which projects into the end member 36.

The snubber device of my present invention may be used to reduce or multiply the fluid pressure exerted on the safety valve actuator by increasing or decreasing the relative diameter of the cylinders 32 and 33 and the respective pistons therein, 30a and 30b.

The snubber 12 may be situated either near the well head as shown in FIG. 1, or onshore. A check valve 58 3 is provided in the injection line to prevent back flow from the well.

Although my invention has been described with a degree of particularity by reference to an embodiment thereof useful for ofishore operations, it is within the purview of my invention to utilize the same for either oflshore or onshore operations. Accordingly, the scope of my invention should not be limited to the details above set forth, but should be limited in breadth only by the following claims.

I claim:

1. An apparatus for an underwater well comprising in combination:

a well head operatively aflixed to said well and adapted for connecting well tubing to a production flow line, conduit means for injecting a fluid into said well through said well head,

a valve proximate said well head for closing ofl said flow line in response to an increase or decrease in pressure in said production flow line,

a spring biased mechanism including a spring operatively connected to said valve,

means associated with said valve and including a valve control fluid, for operating said valve against the force of said spring, when the pressure on said valve control fluids exceeds the tension on said spring and means in fluid communication with and driven by said injection fluid for displacing said valve control fluid to actuate said valve operating means and thereby operate said valve.

2. The apparatus of claim 1 wherein said valve operating means includes a fluid movable piston and the displacement of said valve control fluid moves said piston to operate said valve.

3. The apparatus of claim 1 wherein said-means for displacing said valve control fluid comprises a snubber with a floating piston therein, said piston having a central portion of reduced diameter with packing means associated therewith for reducing fluid entry into said central portion, and

means associated with said snubber for limiting the amount of pressure transmitted through said valve control fluid by displacement thereof.

4. The apparatus of claim 1 wherein said valve operating means are arranged and constructed to hold said valve normally open against the force of said spring.

5. An apparatus for use on an underwater well comprising in combination:

a well head operatively aflixed to said well and adapted for connecting well tubing to a production flow line, conduit means for injecting a fluid into said well through said well head,

a valve proximate said well head for closing oflf said flow line in response to an increase or decrease in pressure in said flow line,

means associated with said valve and including a valve control fluid for holding said valve open with respect to flow from said well tubing through said well head and said flow line,

means driven by said injection fluid for displacing said valve control fluid to hold said valve open, and

means operatively connected to said valve for closing said valve when the displacement pressure on said valve control fluid is released.

References Cited UNITED STATES PATENTS 2,672,881 3/1954 Jay 137-500 X 2,728,547 12/1955 Crookston 25l57 X 3,146,681 9/1964 Sheesley 92--13 3,228,472 1/1966 Rhoads 166-75 X CHARLES E. OCONNELL, Primmy Examiner.

N. C. BYERS, Assistant Examiner. 

1. AN APPARATUS FOR AN UNDERWATER WELL COMPRISING IN COMBINATION: A WELL HEAD OPERATIVELY AFFIXED TO SAID WELL AND ADAPTED FOR CONNECTING WELL TUBING TO A PRODUCTION FLOW LINE, CONDUIT MEANS FOR INJECTING A FLUID INTO SAID WELL THROUGH SAID WELL HEAD, A VALVE PROXIMATE SAID WELL HEAD FOR CLOSING OFF SAID FLOW LINE IN RESPONSE TO AN INCREASE OR DECREASE IN PRESSURE IN SAID PRODUCTION FLOW LINE, A SPRING BIASED MECHANISM INCLUDING A SPRING OPERATIVELY CONNECTED TO SAID VALVE, 